LinuxCNC 2.9 runs with relative high max jitter on the preempt-rt kernel (100k+ ns Max Jitter). On the RTAI Kernel I'm getting ~10k Max Jitter.
I tried to install Debian 12 from the normal installer disk and then install linuxcnc, but this resulted in a segfault when running linuxcnc, but haltest and latency-test worked fine... idk why.
Then follow the linuxcnc install instructions.
wget https://www.linuxcnc.org/linuxcnc-install.sh
sudo bash linuxcnc-install.sh
I commented out the
deb-srcline in /etc/apt/sources.list.d/linuxcnc.list after installation and removed 2.9-uspace from the deb line.
Remove preempt-rt related packages:
sudo apt purge -y 'linux-image-rt-*' \
'linuxcnc-uspace*' \
linuxcnc-doc-en \
linux-headers-rt-amd64 \
linux-libc-dev
Finally, install the RTAI Kernel and linuxcnc packages:
# Install the RTAI kernel
sudo apt install -y linux-image-5.4.258-rtai-amd64 \
linux-headers-5.4.258-rtai-amd64 \
rtai-modules-5.4.258 \
linux-libc-dev=5.4.258-rtai-amd64-2
# Check the libc version matches (5.4.258)
apt policy linux-libc-dev
# Install linuxcnc (RTAI)
sudo apt install -y --no-install-recommends linuxcnc
Install the QTVCP dependencies:
/usr/lib/python3/dist-packages/qtvcp/designer/install_script
And test to make sure QTVCP is working:
qtvcp -d test_panel
Remove raspi-firmware and preempt-rt related packages:
sudo dpkg --purge raspi-firmware
sudo apt purge -y 'linux-image-rt-*' \
'linuxcnc*' \
'linuxcnc-doc-*' \
linux-libc-dev
Finally, install the RTAI Kernel and linuxcnc packages:
# Install the RTAI kernel
sudo apt install -y linux-image-5.4.258-rtai-amd64 \
linux-headers-5.4.258-rtai-amd64 \
rtai-modules-5.4.258 \
linux-libc-dev=5.4.258-rtai-amd64-2
# Check the libc version matches (5.4.258)
apt policy linux-libc-dev
NOTE: Don't install from debs, install from source below.
# DEPRECATED
#export RTAI_VERSION=4.9.294
#cd ~/Downloads
#mkdir rtai-${RTAI_VERSION}
#cd rtai-${RTAI_VERSION}
## download the kernel
#wget https://github.com/NTULINUX/RTAI/releases/download/v5.3.3-gnu11/linux-headers-4.19.294-rtai-amd64_4.19.294-rtai-amd64-1_amd64.deb
#wget https://github.com/NTULINUX/RTAI/releases/download/v5.3.3-gnu11/linux-image-4.19.294-rtai-amd64_4.19.294-rtai-amd64-1_amd64.deb
#wget https://github.com/NTULINUX/RTAI/releases/download/v5.3.3-gnu11/linux-libc-dev_4.19.294-rtai-amd64-1_amd64.deb
#wget https://github.com/NTULINUX/RTAI/releases/download/v5.3.3-gnu11/rtai-modules-4.19.294_5.3.3-linuxcnc-delta_amd64.deb
## install
#sudo dpkg -i *.deb
(if not installing from source) Switch to the RT sources and install linuxcnc:
# comment out the uspace sources
sed -i '1,2 s/^/#/' /etc/apt/sources.list.d/linuxcnc-uspace.list
# use the rt sources
echo 'deb [arch=amd64,arm64 signed-by=/etc/apt/trusted.gpg.d/linuxcnc.gpg.key.binary.gpg] https://www.linuxcnc.org/ bookworm base 2.9-rt' > /etc/apt/sources.list.d/linuxcnc.list
# clear apt cache and update
sudo apt-get clean && sudo apt update
# Install linuxcnc (RTAI)
sudo apt install -y --no-install-recommends linuxcnc
Freeze the header and libc versions we installed:
sudo apt-mark hold linux-headers-amd64
sudo apt-mark hold linux-libc-dev
To boot the RTAI kernel, set grub to save the last booted kernel by editing /etc/default/grub:
GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true
Run sudo update-grub then reboot and select the RTAI kernel from the advanced grub menu on the next boot.
Switch to xfce and lightdm (LinuxCNC does not run on gnome it seems):
sudo apt install -y xfce4 xfce4-session xfce4-goodies lightdm
sudo dpkg-reconfigure lightdm
Install TurboVNC (in a root shell):
wget -q -O- https://packagecloud.io/dcommander/turbovnc/gpgkey | \
gpg --dearmor >/etc/apt/trusted.gpg.d/TurboVNC.gpg
pushd /etc/apt/sources.list.d
wget https://raw.githubusercontent.com/TurboVNC/repo/main/TurboVNC.list
popd
sudo apt update
sudo apt install -y turbovnc
Switch to xfce:
# switch to xfce
echo '$wm = "xfce";' > ~/.vnc/turbovncserver.conf
Run the server:
# add the path to the bash profile
echo 'export PATH=/opt/TurboVNC/bin:${PATH}' > ~/.bashrc
# open a new shell
# run server
vncserver
Follow this guide: https://github.com/NTULINUX/RTAI/blob/master/README.INSTALL and https://linuxcnc.org/docs/html/code/building-linuxcnc.html:
Remove all other sources:
sudo apt-mark unhold linux-libc-dev linux-headers-amd64
sudo dpkg --purge raspi-firmware
sudo apt purge -y 'linux-image-rt-*' \
'linuxcnc*' \
'linuxcnc-doc-*' \
linux-libc-dev
sudo apt install -y git
Install dependencies:
sudo apt install -y libc6-dev \
bison \
flex \
libncurses-dev
Get the RTAI Source:
# clone RTAI
cd ~/src/
git clone https://github.com/NTULINUX/RTAI.git
# checkout the code to match kernel version 4.19.265 (in the RTAI docs)
git checkout v5.3.3-delta
Then get the linux kernel source and patch it in a root shell:
cd /usr/src
sudo wget https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.19.265.tar.xz
sudo tar xf linux-4.19.265.tar.xz
sudo ln -sfv linux-4.19.265 linux
cd linux
for i in "/home/cnc/src/RTAI/ksrc/v4.19.265/"*.patch ; do patch -p1 < "${i}" ; done
make olddefconfig
make menuconfig
I changed the following config options:
- "Kernel hacking" -> "Compile-time checks and compiler options" -> "Strip assembler-generated symbols during link". -> False
Then build:
make bzImage && make modules
make install && make modules_install
Note: to re-build with changes, first run
make cleanthen the make commands above again.
Clone the source:
cd ~/src/
# clone
git clone https://github.com/LinuxCNC/linuxcnc.git linuxcnc-dev
cd linuxcnc-dev
# checkout tag version:
git checkout v2.9.2
# install dependencies
./debian/configure
sudo apt-get -y build-dep .
# check deps
sudo apt-get install -y dpkg-dev
dpkg-checkbuilddeps
Lock memory (in a root shell):
echo '* - memlock 20480' > /etc/security/limits.d/linuxcnc.conf
Configure:
cd ~/src/linuxcnc-dev/src
./autogen.sh
# a specific kernel
./configure --with-realtime=/usr/realtime-5.4.258-rtai-amd64/
# make
make
sudo make setuid
Run linuxcnc:
cd ~/src/linuxcnc-dev
# setup environment
. scripts/rip-environment
linuxcnc
Tail debug logs (syslog):
sudo journalctl -kf
View logs from last boot:
SYSTEMD_COLORS=1 journalctl -b -1 -k | less +G -r